If you still have the commitment letter that you would have received when you originally took your mortgage, it should be stated on the letter if the mortgage is insured, but if not, aside from contacting your current lender to find out, here are a few ways you may be able to tell if it is insured or not:
1) If you purchased your home with a down payment of less than 20% and have not refinanced the mortgage since you purchased, it would likely be insured. Even if you switched your mortgage to a different lender at the end of a term, as long as there was no increase to the mortgage, it is likely insured.
2) If you purchased with a down payment 20% or more, refinanced the mortgage at any point, if your mortgage has a Home Equity Line of Credit component to it, or your mortgage is with a non-federally regulated lender, it is not likely insured.
In this video Jeff Laberge explains all you need to know about default insurance .